Electrical apparatuses, such as transformers, are typically immersed in a fluid to ensure their electrical isolation and/or to assist in heat dissipation or refrigeration of the electrical apparatus. A tank contains the electrical apparatus, which is immersed in a fluid. Some fluids used to immerse these electrical apparatuses include dielectric fluids, such as oil, which assist in transferring heat generated from the electrical apparatus to the inner walls of the tank. The heat is subsequently released to the surrounding atmosphere.
Conventional tanks are formed in the shape of a rectangular enclosure and have four vertical side walls, a horizontal top wall or cover, and a horizontal bottom wall or base. During assembly, five of those walls are preassembled together by welding, leaving an opening to subsequently insert the electrical apparatus and the fluid. Typically, the opening is provided at the top of the tank, however, the opening can be provided at one of the tank side walls.
Once the open structure has been leak tested, the electrical apparatus and fluid are placed within the tank through the opening at the top of the tank. The cover is then welded to the upper edges of the four vertical side walls. The tank is then coated with a corrosion resistant film.
These conventional tanks are typically mounted to a mounting pad and disposed over a rectangular opening formed within the mounting pad. The conventional tanks are rectangularly-shaped so that the tank, once placed over the mounting pad opening, conceals the rectangular opening of the mounting pad, thereby preventing gaps formed between the mounting pad opening and the tank. The mounting pad opening must be completely covered. One reason for completely covering the mounting pad opening is to prevent bees, snakes, and other critters from entering the openings and creating certain hazardous conditions for maintenance personnel.
For certain types of electrical apparatuses, such as transformers, the depth, width, and length of the tank are determined by the free electrical and mechanical space that is necessary between the internal surface of the tank walls and the external surface of the electrical apparatus immersed within the tank. Since these minimal distances are often overestimated, the internal volume of the tank becomes very large which thereby increases the quantity of fluid that is used within the tank. Additionally, the fluid occupying the corners of the rectangularly-shaped tank do not provide any operational benefit, thereby unnecessarily increasing the quantity of fluid that is used in the tank. As previously mentioned, the tank is rectangularly-shaped so that the tank conceals the rectangularly-shaped mounting pad opening once disposed over it. As a result of using increased quantities of fluid, the weight of the tank is unnecessarily increased. This unnecessary weight increase of the tank requires that support members be provided to the tank to prevent the deformation of the side walls and the base. The increased quantity of fluid used within the tank, the increased material used to fabricate a larger tank, and the use of support members all contribute to the unnecessary increased costs associated with the manufacturing and the operation of these tanks.
Additionally, once the tank has been disposed over the mounting pad opening, the base of the conventional tank is positioned at or very close to the top surface of the mounting pad. As a result, there is a risk of the base and the lower portions of the side walls becoming corroded due to contact with water and/or other corrosive elements resting on the top surface of the mounting pad to which these conventional tanks are mounted. If the corrosion of the tank is not detected at an early stage, there is a risk of the tank developing leaks through the base and the lower portions of the side walls.
Therefore it is desirable to minimize or eliminate one or more concerns of the types discussed above and to otherwise improve these tanks.